Question

A Girl has drawing a pookelam for
Onam festival .In the outer Circle
she has 300 flowers and in each circle she reduced number of flowers by 10. Total there was 20 circle. How many flowers used for
making this pookalam?​

Answer 1

Answer:

Your answer is 200

Step-by-step explanation:

Please mark me as brilliant

Answer 2

Total number of flowers used is 4100

Given:

A Girl has drawing a pookalam for Onam festival.

Number of flower in the outer Circle she kept 300 flowers

In each circle she reduced number of flowers by 10.

Total number of circles are 20  

To find:

How many flowers used for entire pookalam

Solution:

Given there are 20 circles

Number of flower in last circle 300

For each circle 10 flower are reduced

then number flowers in next circles 290 280, 270...

Here the order of number of flowers = 300, 290, 280...  is a AP

where first term = 300, common difference = - 10

Total number of terms = 20

Total number of flowers used = sum of 20 terms

As we know sum of n terms = $\frac{n}{2} [ 2a+(n-1)d ]$  

⇒ Sum of 20 terms = $\frac{20}{2} [ 2a+(20-1)d ]$

= 10 [ 2a +19d]

= 10 [ 2(300) +19 (-10) ]

= 10 [ 600 - 190]

= 10 [ 410 ] = 4100

Total number of flowers used = 4100

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